Improving the appearance of the skin has been the goal of many esthetic products and procedures for many years, since a tight skin, without wrinkles or cellulite, has a younger and more appealing appearance. Apart from age related changes, the skin also suffers from exposure to chemical and physical injuries, such as tobacco, cosmetics, esthetics and radiation from the sun and other sources. Those factors contribute to the decrease in collagen production, to reduced elasticity, and the appearance of wrinkles.
A few main approaches to tightening of the skin are common practice today. The surgical approach carries disadvantages related to the anesthesia, the surgical complications, and the healing process, which may cause scars. The chemical peel approach usually involves injury to the outermost layer of the skin—the epidermis—which may cause discoloration. Since collagen fibers are found in the dermis—the subcutaneous layer of the skin, and since heat was shown to contract these fibers and generate their production [Zelickson B D, Kist D, Bernstein E, Brown D B, Ksenzenko S, Burns J, Kilmer S, Mehregan D, Pope K. Histological and ultrastructural evaluation of the effects of a radiofrequency-based nonablative dermal remodeling device: a pilot study. Arch Dermatol. 2004 February; 140(2):204-9], methods of differentially heating the dermis (deep tissue diathermy) have recently arisen.
A unique method of treating the dermis is called Pulsed Electromagnetic Fields (PEMF) therapy. This method usually employs electromagnetic radiation of different frequencies—ranging from static magnetic fields, through extremely low frequencies (ELF) to higher radiofrequencies (RF)—administered in pulses.
PEMF works in few ways. Due to the radiation absorbed in the tissue, it can be heated to various temperatures, depending on the power applied, the frequency transmitted, and more importantly the tissue characteristics. Eventually, the tissue can be warmed to denaturation temperatures, which cause coagulation necrosis and tissue damage. It can also be heated to lower temperatures, which proved to result in the afore-mentioned contraction of collagen fibers.
Another modus operandi involves non thermal effects. These rely on specific tissue components and their reaction to the applied radiation characteristics. These effects might be due to large charged molecules and their reaction to various frequencies and frequency harmonies, charged small ions in the cell membranes affecting the cells function and reactions to hormones and chemical signals, charged small ions in the extracellular space and other poorly understood mechanisms.
Furthermore, applying the radiation in pulses was also found to have non thermal effects. Yet more, only a specific combination of frequency, duty cycle and transmitted power achieve a specific tissue response. Recent scientific research has confronted these challenges and found the PEMF characteristics needed for the desired biophysical response.
It is now commonly accepted that weak electromagnetic fields (EMF) administered in pulses are capable of initiating various healing processes in fractures, multiple sclerosis and Parkinson's disease, and even delivering pain relief; however it seems that most of the conditions that seem most likely to respond to PEMF are musculoskeletal. The FDA has allowed the use of pulsed radiofrequency electromagnetic field for treatment of pain and edema in superficial soft tissues two decades ago. [Rosch, P. J., Markov, M. S., eds. Bioelectromagnetic Medicine, Marcel Dekker, NY, 251-264].
The use of PEMF can also be recruited for cosmetic purposes as described above. Several studies have addressed the effect of PEMF on dermal components. For example, in vivo trials showed that pulsed electromagnetic field of certain field intensities and frequencies increased epidermal collagen synthesis [Ahmadian S, Zarchi S R, Bolouri B. Effects of extremely-low-frequency pulsed electromagnetic fields on collagen synthesis in rat skin. Biotechnol Appl Biochem. 2006 February; 43(Pt 2):71-5]. This new formed collagen increases skin elasticity and rejuvenates its appearance.
In vitro trials showed that PEMF increased the degree of endothelial cell tubulization and proliferation, and augmented angiogenesis primarily by stimulating endothelial release of FGF-2, inducing paracrine and autocrine changes in the surrounding tissue [Tepper O M et al. Electromagnetic fields increase in vitro and in vivo angiogenesis through endothelial release of FGF-2. FASEB J. 2004 August; 18(11):1231-3. Epub 2004 Jun 18]. Angiogenesis, the sprouting of new blood vessels, increases blood flow to the tissue, which in turn increases oxygen and nutritional substances delivery to the tissue. This effect is most beneficial for an injured tissue, promoting rapid and improved healing. The growth factor released further enhances the healing process, both in quality and time of improvement.
The scientific evidence of the effect of PEMF on tissues was utilized in various applications. For example, US20050182462A1 discloses healthy deep tissue heating using PEMF for the purpose of causing contraction and tightening of the skin.
PEMF has also been used to improve skin wound healing. For example, WO08064272 discloses a method of treating a severe diabetic ulcer using PEMF. The patent also discloses the addition of intermittent compression therapy (ICT) and the use of low intensity ultrasound (up to 50 W/cm2), the latter aimed at inhibiting microbial growth.
Other methods of heating the dermis used non pulsating RF radiation, applied by antenna or electrodes. For example, WO98005380 discloses a method of tightening skin using an RF electromagnetic energy delivery device.
Improving the results of skin tightening based on dermis diathermy is still a long felt need, both for esthetic and therapeutic purposes.